This invention relates to an improved keyless fob as used in conjunction with a vehicle receiving module which opens the vehicle door locks and/or trunk, for example, in response to transmissions from the fob.
Systems for unlocking automobile doors and trunks include conventional keys, coded keypads on the automobile itself and lock systems which employ remote transmission, as for example from a key chain fob. While conventional keys and coded keypads may provide high security, many drivers today prefer to use keyless fobs for their greater convenience. Such fobs generally include one or more pushbutton keys or actuators that, when pressed, cause the fob to emit a coded transmission including both an identification code for the particular fob and information to authorize the execution of a particular action or vehicle function, e.g. unlocking the automobile doors or opening the trunk. A control module or receiver on the automobile at which the fob is pointed picks up the coded transmission and decodes it. Such a control module constitutes, or is part of, the general electronic module (GEM) controlling the electrical system of the automobile and powered by the standard automobile battery. If the identification code in the transmission identifies the fob as one assigned to that automobile, the control module causes the electrical system of the automobile to execute the indicated action. As a result, the driver of the automobile can unlock the door and/or the trunk for example as he or she approaches the automobile. Such lock systems are referred to as remote keyless entry (RKE) systems.
Typically RKE or keyless fob systems for automobiles are designed so that a user can push a fob button and actuate a vehicle function from at least 10 meters from the vehicle and upwards to 40 or 50 meters from the vehicle as a matter of design choice. A drawback to this type of conventional keyless fob involves the typical situation of when a user""s hands may not be free to push a fob button as he/she approaches the related automobile. For example, a user may be carrying bags of groceries whereby the fob could not be actuated without having to unload the bags first; or, before picking up the bags the user may be beyond the range of the fob signal being received and even if the fob was operable at a distance significantly greater than the typical 10 to 50 meters range from the vehicle, the user may not feel comfortable opening his/her trunk or doors at such a distance and then having to approach the vehicle with hands encumbered.
Accordingly, an the object of the invention is to provide a semi-passive keyless fob entry system for an automobile wherein vehicular functions can be preprogramed to occur in a hands free fashion as the user approaches the vehicle.
It is another object of the invention to provide a keyless fob to operate in the above manner wherein the preprogrammed vehicular function will occur only when the user is within a relatively close, pre-determined distance of the vehicle; in this manner the user could return to a grocery store, for example, if something has been forgotten and not have to be concerned about placing bags down and re-locking the doors or trunk of the automobile involved.
It is yet another object of the invention to provide a keyless fob for an automobile which does not in any way compromise the user""s safety in the sense of having preprogrammed functions occur prematurely in a hands free manner as the user approaches an automobile.
It is still another object of the invention to provide a keyless fob entry system for an automobile (or any device or structure) in which the hands free mode of operation can easily and conveniently be used with the conventional manual mode of operation of such fobs (wherein a button is simply pushed within the operating range of the fob with respect to the vehicle to immediately cause a vehicular function to occur).